"If they obtain nuclear weapons capability, then I think other nations across the Middle East will want to develop nuclear weapons.

"And so, the most serious round of nuclear proliferation since nuclear weapons were invented would have begun with all the destabilising effects in the Middle East. And the threat of a new Cold War in the Middle East without necessarily all the safety mechanisms. That would be a disaster in world affairs."

There are growing fears that President Mahmoud Ahmadinejad will not be deterred by sanctions, the preferred route of the US and Britain to pressure the regime into abandoning its nuclear weapons programme.